A method and system for in-situ permeability coefficient determination of a water stop curtain

Abstract

The application discloses a kind of in-situ permeability coefficient determination method and system of water-stop curtain, the method comprises the following steps: drilling and well washing operation are carried out to water-stop curtain;Water stop plug is added in test hole, the position and length of test section are determined, then water injection is pressurized, and flow data and water table data are recorded;Judgment is made to cross section type and stratum attribute, and first type judgment information and second type judgment information are obtained;According to first type judgment information, second type judgment information, flow data and water table data, permeability coefficient is calculated in different cases.The system comprises drilling cleaning module, position confirmation module, water injection pressurization module, cross section judgment module, seepage judgment module and permeability coefficient calculation module, by using the application, the in-situ permeability coefficient of water-stop curtain can be accurately obtained while ensuring the timeliness and cost of test.The application is a kind of in-situ permeability coefficient determination method and system of water-stop curtain, which can be widely applied in in-situ engineering detection technical field.

Description

Technical Field

[0001] This invention relates to the field of in-situ engineering testing, and in particular to a method and system for determining the in-situ permeability coefficient of a water-stop curtain. Background Technology

[0002] The structural forms of water-stop curtains include pile retaining walls and diaphragm walls. Besides providing support during underground engineering construction, their seepage-blocking capacity is also a crucial factor in ensuring construction safety. The seepage resistance of diaphragm walls directly affects the stability of the surrounding hydrogeology. If the permeability does not meet requirements, it may cause problems such as a drop in groundwater level, deformation of the water-stop curtain, and settlement of nearby buildings, seriously affecting the safety of the construction itself and the stability of the surrounding site. Current evaluations of their structural seepage resistance generally rely on theoretical calculations based on the material's inherent seepage resistance or on indoor permeability tests through core drilling. However, these methods cannot reflect the in-situ permeability performance of the water-stop curtain under actual operating conditions.

[0003] Currently, commonly used methods for testing the permeability of underground structures include theoretical calculations, laboratory testing, and in-situ testing. In theoretical calculations, engineers infer the permeability of diaphragm walls based on the impermeability of concrete or cement-soil. Laboratory testing involves core sampling to measure the permeability coefficient of cylindrical specimens, thus determining the permeability at that location. Additionally, there are methods that involve installing dewatering wells within the wall and conducting pumping tests to obtain the structure's water-blocking capacity. However, theoretical calculations only reflect the inferred permeability under ideal conditions, and core sampling yields laboratory test parameters that are detached from actual site conditions, both having limitations. The impermeability of water-stop curtains varies with construction quality and the surrounding environment; in-situ testing can better reflect the actual situation. While pumping tests within the wall can obtain the in-situ water-blocking performance of the retaining wall, the testing time and economic costs are relatively high. Summary of the Invention

[0004] To address the aforementioned technical problems, the objective of this invention is to provide a method and system for determining the in-situ permeability coefficient of a water-stop curtain, which can accurately obtain the in-situ permeability coefficient of the water-stop curtain while ensuring the timeliness and cost of the experiment.

[0005] The first technical solution adopted in this invention is: a method for determining the in-situ permeability coefficient of a water-stop curtain, comprising the following steps:

[0006] Test holes were obtained by drilling holes in the structure of the water-stop curtain;

[0007] The test well was flushed to obtain a test well with unobstructed seepage channels;

[0008] A water-stop plug was inserted into the test hole to determine the location and length of the test section;

[0009] Water was injected and pressurized into the test section of the test well, and the flow rate and water level data were recorded.

[0010] The cross-sectional type of the water-stop curtain is determined to obtain the first type of judgment information;

[0011] Based on geological data, the internal stratigraphic properties of the structure are determined, and the second type of judgment information is obtained.

[0012] Based on the first type of judgment information, the second type of judgment information, flow data and groundwater level data, the permeability coefficient is calculated according to different situations.

[0013] Furthermore, the step of performing well-washing operations on the test borehole to obtain a test borehole with unobstructed seepage channels specifically includes:

[0014] Pour the well-washing medium into the test hole to dissolve soluble impurities;

[0015] The solution containing dissolved impurities is poured out through the test hole, while the insoluble impurities are carried out of the test hole, resulting in a test hole with unobstructed seepage channels.

[0016] This preferred step flushes out impurities from the wellbore, preventing tiny debris from clogging the seepage channels inside the structure during water pressure and thus avoiding distorted results.

[0017] Furthermore, the step of injecting water and pressurizing the test section of the test well, and recording the flow rate data and water level data, specifically includes:

[0018] Water was injected at constant pressure, and the flow rate was recorded as a curve over time.

[0019] An observation hole was added outside the wall, and an electronic water gauge was installed inside the observation hole to detect changes in the groundwater level.

[0020] By employing this optimized procedure, the flow rate reading can be more accurate when using constant pressure water injection compared to controlling the flow rate input during water pressurization.

[0021] Furthermore, the step of calculating the permeability coefficient based on the first type of judgment information, the second type of judgment information, flow data, and groundwater level data, specifically includes:

[0022] S1. When the first type of judgment information is that the cross-section is circular, the second type of judgment information is that vertical seepage exists, and the change of groundwater level is considered, the in-situ permeability coefficient calculation expression is as follows:

[0023] k=(Q / 2π)×[1 / (q l2 +q r2 )]

[0024]

[0025]

[0026] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l2 q r2 The values ​​represent intermediate coefficients in the calculation process, P represents the test section pressure, L represents the test section length, and R represents the intermediate coefficients. w H represents the radius of the pile, r represents the radius of the test hole, h1 represents the distance from the top of the test section to the impermeable layer, and H represents the radius of the test hole. U0 H represents the thickness of the vadose zone before the test. W0 ρ represents the thickness of the unwater aquifer before the test, Δh represents the change in water level during the test, ρ represents the density of water, and g represents the gravity coefficient.

[0027] S2. When the first type of judgment information is that the cross-section is circular, the second type of judgment information is that there is no vertical seepage, and the change of groundwater level is considered, the in-situ permeability coefficient calculation expression is as follows:

[0028] k=(Q / 2π)×[1 / (q r2 )]

[0029] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q r2 This represents intermediate coefficients in the calculation process, and its specific representation is consistent with that in S1.

[0030] S3. The first type of judgment information is that the cross-section is rectangular, and the second type of judgment information is that vertical seepage exists. Considering the change of groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0031] k=(Q / 4)×[1 / (q l4 +q r4 )]

[0032]

[0033]

[0034] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l4 q r4 The following are intermediate coefficients used in the calculation process: P represents the test section pressure, L represents the test section length, r represents the test hole radius, h1 represents the distance from the top of the test section to the waterproof layer, and H represents the intermediate coefficients used in the calculation process. U0 H represents the thickness of the vadose zone before the test. W0 The value represents the thickness of the unconfined aquifer before the experiment, Δh represents the change in water level during the experiment, ρ represents the density of water, g represents the gravitational coefficient, and B... w n represents the thickness of the diaphragm wall. RThis is the dimension factor for drilling holes in diaphragm walls.

[0035] S4. The first type of judgment information is that the cross-section is rectangular, and the second type of judgment information is that there is no vertical seepage. Considering the change of groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0036] k=(Q / 4)×[1 / (q r4 )]

[0037] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q r4 This represents intermediate coefficients in the calculation process, and its specific representation is consistent with that in S3.

[0038] S5. The first type of judgment information is that the cross-section is circular, and the second type of judgment information is that vertical seepage exists. Without considering changes in the groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0039] k=(Q / 2π)×[1 / (q l1 +q r1 )]

[0040]

[0041]

[0042] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l1 q r1 The values ​​represent intermediate coefficients in the calculation process, P represents the test section pressure, L represents the test section length, and R represents the intermediate coefficients. w H represents the radius of the pile, r represents the radius of the test hole, h1 represents the distance from the top of the test section to the impermeable layer, and H represents the radius of the test hole. U0 H represents the thickness of the vadose zone before the test. W0 ρ represents the thickness of the unconfined aquifer before the test, g represents the density of water, and g represents the gravity coefficient.

[0043] S6, S7, and S8 correspond to the cases of S2, S3, and S4 where the change in groundwater level is not considered. Their calculation process is the same as that of S5, except that the change in groundwater level is removed.

[0044] This optimized process allows for the calculation of the in-situ permeability coefficient under different cross-sections and vertical seepage conditions of the water-stop curtain. It also allows for the selection of whether to consider changes in the water level based on actual conditions, thereby reducing the cost of setting up observation holes.

[0045] The second technical solution adopted in this invention is: an in-situ permeability coefficient measurement system for a water-stop curtain, comprising:

[0046] The drilling and cleaning module is used to drill holes in the structure of the water-stop curtain and to clean the holes to obtain test holes with unobstructed seepage channels.

[0047] The position confirmation module is used to insert a water-stop plug into the test hole to determine the position and length of the test section;

[0048] The water injection and pressurization module is used to inject water and pressurize the test section of the test hole, and record the flow rate data and water level data;

[0049] The cross-section judgment module is used to judge the cross-section type of the water-stop curtain and obtain the first type of judgment information;

[0050] The seepage judgment module determines the internal strata properties of the structure based on geological data, and obtains the second type of judgment information;

[0051] The permeability coefficient calculation module calculates the permeability coefficient based on the first type of judgment information, the second type of judgment information, flow data, and groundwater level data, depending on the situation.

[0052] The beneficial effects of the method and system of this invention are as follows: This invention constructs a smooth water-stop curtain test section and injects water and pressurizes the test section to obtain flow rate data and groundwater level data; by judging the actual cross section and stratum properties, the in-situ permeability coefficient is calculated according to different situations, which can accurately obtain the in-situ permeability coefficient of the water-stop curtain while ensuring the timeliness and cost of the test. Attached Figure Description

[0053] Figure 1 This is a flowchart of the steps for determining the in-situ permeability coefficient of a water-stop curtain according to the present invention.

[0054] Figure 2 This is a structural block diagram of an in-situ permeability coefficient measurement system for a water-stop curtain according to the present invention;

[0055] Figure 3 This is a schematic diagram of the specific calculation structure of the in-situ permeability coefficient determination method for a water-stop curtain according to the present invention;

[0056] Figure 4 This is a schematic diagram of the drilling and water pressure operation for the in-situ permeability coefficient determination method of a water-stop curtain according to the present invention.

[0057] Attached diagram descriptions: 1. Water pressure test section; 2. Test section water stop plug; 3. Pressure gauge; 4. Connecting pipeline; 5. High-pressure stabilizing water pump; 6. Flow meter; 7. Water supply tank; 8. Observation hole; 9. Test hole. Detailed Implementation

[0058] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0059] Reference Figure 1 and Figure 3 This invention provides an in-situ method for determining the permeability coefficient of a water-stop curtain, the method comprising the following steps:

[0060] like Figure 4 As shown, a test hole was drilled vertically at the center of the water-stop curtain structure to obtain the test hole.

[0061] The well-washing medium is poured into the test borehole to dissolve soluble impurities. Then, the solution containing the dissolved impurities is poured out through the test borehole, simultaneously carrying away insoluble impurities, resulting in a test borehole with unobstructed seepage channels. This avoids the possibility of tiny debris clogging the seepage channels inside the structure during water pressure testing, which could distort the results.

[0062] Based on the core drilling data, a water-stop plug was added into the test hole to determine the location of the water-stop plug, and the distance from the top of the test section to the top of the structure and the length of the test section were obtained.

[0063] The test section of the test well was pressurized with water at a constant pressure. The flow rate over time was recorded using a water supply tank, flow meter, high-pressure stabilizing pump, and pressure gauge. Simultaneously, an observation hole was added outside the wall, equipped with an electronic water level gauge to record changes in the groundwater level. Compared to controlling the flow input during pressurized water injection, using constant pressure water injection provides more accurate flow rate readings.

[0064] The cross-sectional type of the water-stop curtain is determined to obtain the first type of judgment information. This invention includes two judgment cases: circular cross-section and rectangular cross-section.

[0065] Based on geological data, the internal strata properties of the structure are determined to obtain the second type of judgment information. This invention includes two cases: considering vertical seepage and not considering vertical seepage. If there is no highly permeable non-uniform stratum outside the water-pressing section, then there is no vertical seepage; if there is a highly permeable non-uniform stratum outside the water-pressing section, then there is vertical seepage.

[0066] Based on the first type of judgment information, the second type of judgment information, flow data and groundwater level data, the permeability coefficient is calculated according to different situations.

[0067] S1. When the first type of judgment information is that the cross-section is circular, the second type of judgment information is that vertical seepage exists, and the change of groundwater level is considered, the in-situ permeability coefficient calculation expression is as follows:

[0068] k=(Q / 2π)×[1 / (q l2 +q r2 )]

[0069]

[0070]

[0071] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l2 q r2 The values ​​represent intermediate coefficients in the calculation process, P represents the test section pressure, L represents the test section length, and R represents the intermediate coefficients. w H represents the radius of the pile, r represents the radius of the test hole, h1 represents the distance from the top of the test section to the impermeable layer, and H represents the radius of the test hole. U0 H represents the thickness of the vadose zone before the test. W0 ρ represents the thickness of the unwater aquifer before the test, Δh represents the change in water level during the test, ρ represents the density of water, and g represents the gravity coefficient.

[0072] S2. When the first type of judgment information is that the cross-section is circular, the second type of judgment information is that there is no vertical seepage, and the change of groundwater level is considered, the in-situ permeability coefficient calculation expression is as follows:

[0073] k=(Q / 2π)×[1 / (q r2 )]

[0074] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q r2 This represents intermediate coefficients in the calculation process, and its specific representation is consistent with that in S1.

[0075] S3. The first type of judgment information is that the cross-section is rectangular, and the second type of judgment information is that vertical seepage exists. Considering the change of groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0076] k=(Q / 4)×[1 / (q l4 +q r4 )]

[0077]

[0078]

[0079] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l4 q r4 The following are intermediate coefficients used in the calculation process: P represents the test section pressure, L represents the test section length, r represents the test hole radius, h1 represents the distance from the top of the test section to the waterproof layer, and H represents the intermediate coefficients used in the calculation process. U0H represents the thickness of the vadose zone before the test. W0 The value represents the thickness of the unconfined aquifer before the experiment, Δh represents the change in water level during the experiment, ρ represents the density of water, g represents the gravitational coefficient, and B... w n represents the thickness of the diaphragm wall. R This is the dimension factor for drilling holes in diaphragm walls.

[0080] S4. The first type of judgment information is that the cross-section is rectangular, and the second type of judgment information is that there is no vertical seepage. Considering the change of groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0081] k=(Q / 4)×[1 / (q r4 )]

[0082] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q r4 This represents intermediate coefficients in the calculation process, and its specific representation is consistent with that in S3.

[0083] S5. The first type of judgment information is that the cross-section is circular, and the second type of judgment information is that vertical seepage exists. Without considering changes in the groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0084] k=(Q / 2π)×[1 / (q l1 +q r1 )]

[0085]

[0086]

[0087] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l1 q r1 The values ​​represent intermediate coefficients in the calculation process, P represents the test section pressure, L represents the test section length, and R represents the intermediate coefficients. w H represents the radius of the pile, r represents the radius of the test hole, h1 represents the distance from the top of the test section to the impermeable layer, and H represents the radius of the test hole. U0 H represents the thickness of the vadose zone before the test. W0 ρ represents the thickness of the unconfined aquifer before the test, g represents the density of water, and g represents the gravity coefficient.

[0088] S6. The first type of judgment information is that the cross-section is circular, and the second type of judgment information is that there is no vertical seepage. Without considering changes in the groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0089] k=(Q / 2π)×[1 / (q r1 )]

[0090] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q r1 This represents intermediate coefficients in the calculation process, and its specific representation is consistent with that in S5.

[0091] S7. The first type of judgment information is that the cross-section is rectangular, and the second type of judgment information is that vertical seepage exists. Without considering changes in the groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0092] k=(Q / 4)×[1 / (q l3 +q r3 )]

[0093]

[0094]

[0095] Where j represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q l3 q r3 The following are intermediate coefficients used in the calculation process: P represents the test section pressure, L represents the test section length, r represents the test hole radius, h1 represents the distance from the top of the test section to the waterproof layer, and H represents the intermediate coefficients used in the calculation process. U0 H represents the thickness of the vadose zone before the test. W0 The value represents the thickness of the unconfined aquifer before the experiment, ρ represents the density of water, g represents the gravitational coefficient, and B... w n represents the thickness of the diaphragm wall. R This is the dimension factor for drilling holes in diaphragm walls.

[0096] S8. The first type of judgment information is that the cross-section is rectangular, and the second type of judgment information is that there is no vertical seepage. Without considering changes in the groundwater level, the in-situ permeability coefficient calculation expression is as follows:

[0097] k=(Q / 4)×[1 / (q r3 )]

[0098] Where k represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, and q r3 This represents intermediate coefficients in the calculation process, and its specific representation is consistent with that in S7.

[0099] like Figure 2 As shown, an in-situ permeability coefficient measurement system for a water-stop curtain includes:

[0100] The drilling and cleaning module is used to drill holes in the structure of the water-stop curtain and to clean the holes to obtain test holes with unobstructed seepage channels.

[0101] The position confirmation module is used to insert a water-stop plug into the test hole to determine the position and length of the test section;

[0102] The water injection and pressurization module is used to inject water and pressurize the test section of the test hole, and record the flow rate data and water level data;

[0103] The cross-section judgment module is used to judge the cross-section type of the water-stop curtain and obtain the first type of judgment information;

[0104] The seepage judgment module determines the internal strata properties of the structure based on geological data, and obtains the second type of judgment information;

[0105] The permeability coefficient calculation module calculates the permeability coefficient based on the first type of judgment information, the second type of judgment information, flow data, and groundwater level data, depending on the situation.

[0106] The content of the above method embodiments is applicable to this system embodiment. The specific functions implemented in this system embodiment are the same as those in the above method embodiments, and the beneficial effects achieved are also the same as those achieved in the above method embodiments.

[0107] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A method of determining the in-situ permeability coefficient of a water curtain, characterized in that, The method comprises the following steps: Drilling a structure of the waterproof curtain to obtain a test hole; Adding a waterproof plug into the test hole to determine the location and length of a test section; Pressurizing the test section of the test hole by water injection, and recording flow data and phreatic level data; Judging the cross-sectional type of the waterproof curtain to obtain first type of judgment information; Judging the stratum attribute inside the structure according to geological data to obtain second type of judgment information; According to the first type of judgment information, the second type of judgment information, the flow data and the phreatic level data, the permeability coefficient is calculated in different cases; If there is no non-uniform stratum with strong water permeable layer outside the water injection section, there is no vertical seepage; if there is non-uniform stratum with strong water permeable layer outside the water injection section, there is vertical seepage; When the first type of judgment information is that the cross section is circular, the second type of judgment information is that there is vertical seepage, and the phreatic level change is considered, the in-situ permeability coefficient calculation expression is as follows: wherein represents the in-situ permeability coefficient, represents the average flow rate over the experimental time, represents an intermediate coefficient during the calculation, represents the test section pressure, represents the test section length, represents the radius of the pile, represents the test hole radius, represents the test section top distance to the aquiclude, represents the thickness of the vadose zone before the test, represents the thickness of the phreatic aquifer before the test, represents the change in the phreatic surface height over the test time, represents the density of water, represents the gravity coefficient; When the first type of judgment information is that the cross section is circular, the second type of judgment information is that there is no vertical seepage, and the phreatic level change is considered, the in-situ permeability coefficient calculation expression is as follows: When the first type of judgment information is that the cross section is rectangular, the second type of judgment information is that there is vertical seepage, and the phreatic level change is considered, the in-situ permeability coefficient calculation expression is as follows: wherein, denotes an intermediate coefficient in the calculation process, denotes the thickness of the underground continuous wall, is the size coefficient of the diaphragm wall drilling; When the first type of judgment information is that the cross section is rectangular, the second type of judgment information is that there is no vertical seepage, and the phreatic level change is considered, the in-situ permeability coefficient calculation expression is as follows:

2. The method of claim 1, wherein, The method further comprises well washing operation on the test hole, which specifically comprises: Pouring the well washing medium into the test hole to dissolve the soluble impurities; Pouring the solution with dissolved soluble impurities out along the test hole, while taking the insoluble impurities out of the test hole to obtain a test hole with unblocked seepage channel.

3. The method of claim 1, wherein the hydraulic conductivity of the water curtain is determined in situ. The step of pressurizing the test section of the test hole by water injection and recording flow data and phreatic level data specifically comprises: Using constant pressure water injection to record the curve of flow rate changing with time; Adding an observation hole outside the wall, and setting an electronic water level gauge in the observation hole to detect the phreatic level and record the phreatic level change.

4. The method of claim 1, wherein, The method further comprises that, without considering the phreatic level change, the in-situ permeability coefficient calculation expression is as follows: wherein Kp represents the in-situ permeability coefficient, Q represents the average flow rate over the experimental time, C represents an intermediate coefficient during the calculation, P represents the test section pressure, L represents the test section length, R represents the radius of the pile, r represents the test hole radius, D represents the test section top distance to the aquiclude, Z represents the thickness of the vadose zone before the test, H represents the thickness of the phreatic aquifer before the test, p represents the density of water, g represents the gravity coefficient.

5. An in-situ permeability coefficient measurement system for a water curtain, characterized by, The method for measuring the in-situ permeability coefficient of a waterproof curtain according to claim 1 comprises: A drilling and cleaning module for drilling a structure of the waterproof curtain and performing well washing operation on the hole to obtain a test hole with unblocked seepage channel; A location confirmation module for adding a waterproof plug into the test hole to determine the location and length of a test section; A water injection and pressurization module for pressurizing the test section of the test hole by water injection, and recording flow data and phreatic level data; A cross section judgment module for judging the cross-sectional type of the waterproof curtain to obtain first type of judgment information; A seepage judgment module for judging the stratum attribute inside the structure according to geological data to obtain second type of judgment information; A permeability coefficient calculation module for calculating the permeability coefficient in different cases according to the first type of judgment information, the second type of judgment information, the flow data and the phreatic level data.

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